The present invention relates to an emptying device for bulk bags having an inner and outer sack, which is particularly suitable for the dust-free emptying of bulk bags filled with moisture-sensitive, toxic or corrosive fluid bulk materials. The invention also relates to a method for emptying bulk bags using the emptying device according to the invention.
It is known to market fluid bulk materials in large sack-like containers referred to in the following as bulk bags. Bulk bags for receiving corrosive, toxic and/or otherwise sensitive, possibly hygroscopic, bulk materials usually comprise a sealing-tight inner sack, also called an inliner, and a mechanically stable outer sack. The inner sack is usually made of a sufficiently thick film of plastics material or a compound film, for example a plastics material film coated with aluminum. The outer sack is generally made of a natural or synthetic textile material, often a ribbon woven. In their upper region, bulk bags with an inner and outer sack usually comprise a closable filling aperture, which is also used for ventilation during emptying, and carrying loops which allow for handling using lifting tools. Arranged at the base of the bulk bag are the outlet necks, which are fitted within one another and are closed by means of a lower and an upper sack tie, which generally enclose both sacks.
In addition, the outlet neck of the inner sack is welded in a sealing-tight manner, usually beneath the lower sack tie. The tied and/or welded outlet neck of the inner sack can be folded in a suitable manner and arranged within the outlet neck of the outer sack.
In order to empty the bulk bags, the latter are brought over the container which is to be filled by means of the handling tools and are emptied after opening the sack ties. Dust-free emptying of bulk bags is not possible in this manner. For dust-free emptying of bulk bags, various emptying devices have become known in the art.
EP-A 0 637 552 teaches a metering pallet for bulk bags, a container which is open at the top being arranged beneath the opening of a receiving plate for the bulk bag, the side wall of the container comprising a device for opening and closing the container and the underside of the container being connected to a metering device. After placing the bulk bag on top of the receiving plate with the outlet neck reaching into the container, the ties can be opened through the side door in the container. If the inner sack of the bulk bag is made of a material with low flexibility, such as an aluminum-lined compound film, it is not possible to rule out disturbances in the outflow as a result of bridge formations. This is particularly a great disadvantage in cases where access to the emptying device through the side door is not possible on account of the toxic or corrosive character of the product.
A similar device is taught in GB-A 2 250 016: Apart from a receiving dish for receiving the outlet neck and the lower part of the bulk bag and a door in this dish for handling the sack ties, this emptying device also comprises a squeezing device for reducing or completely interrupting the bulk material flow and for retying the sack. This device is also unsuitable for the problem-free emptying of bulk bags, in particular those with an inner sack of low flexibility and/or a welded inner sack, since disturbances during emptying as a result of blockages in the outflow cannot always be avoided, but contact of the contents with the skin is not permissible for hygiene reasons.
It is therefore an object of the present invention to provide an emptying device for bulk bags having an inner and outer sack, by means of which said bags can be reliably emptied in a problem-free manner, without having to come into contact with the contents.
According to a further object, an emptying device is also to be provided that is suitable for emptying bulk bags having an inner sack with low flexibility, particularly for use in the case of dangerous substances.